Plastic packing stuffing-box



H. T. WHEELER PLASTIC PACKING STUFFING BOX IN V EN TOR.

Oct. 9, 1934. E H. T. WHEELER 1,975,886

PLASTIC PACKING STUFFING BOX.

Filed Dec- 22, 1950 2 Sheets-Sheet? 112 sazLo p1 1134. 2810.;

INVENTOR.

1397 g WA Patented Oct. 9, 1934 1525,83;

STATES My invention relates to improvements in apsectioning of thesleeve 6. A series of right and plying plastic packing to stufiing-boxesand its left hand multiple square grooves are formed chief advantage isa capability of securing a tight in the bore of the sleeve 6 making thegrooves joint under high pressures when subjected to ex- I 22 andleaving the lands 23 and 24 between the 5. cessive temperatures oradverse chemical reacgrooves. The face of each groove which, is dition.rected toward the pressure is cut at an acute am- This particularinvention consists of forming gle W th t e Su ace of the p forming aright and left-hand helical grooves in the sursharp lip. If h ran i fr mv um to presface of a stuihng-box and shaping them so that Sure, a p Whe formed on each of the pp 10 the plastic packing injected Willmaintaina tight f Th pr j cti of h he is shown on one joint under the extremesof quick rise and fall r v n y to avoid f i n f dotted l n of pressurein the presenceof harsh media, by A pa s 29 is made the entire length ofthe properly maintaining the density and position or Sleeve 6 a dConnected t the grOOVeS 22 at a th m ti te i L convenient point near thesource of pressure.

15 A further advantage of this invention is the Th passage 0 does n in rany other p use of a spring-loaded-reservoir to inject or withtion ofthe grooves nor the outer surface of the draw packing from the grooves,according to the sleeve 6. vibration or position'of the rod. R urnin n wto Fi ur 1, a di c 9 havin A still further and important advantage isthe cl arance ar u d t p u 2 a d being a loose 20 use of a samplerconnected to an injection point fit t the S U fi -bOX Chamber 1, isinserted bein t g ooves, whereby Samples of the packing fore the sleeve6 to close the intersection of the in use can be withdrawn and examined,coincigrooves 22 With the end of the Sleeve Such dent with the injectionof new packing, 'withintersections being indicated in Figure 3. A outstopping the machine. Y gasket 7 is inserted between the disc 9 and the25 Further objects and advantages of this invenguide bushing 8 to make apressure tight joint tion will appear With the description of theconbetween the bottom of the chamber 1 and the struction which follows,accompanied by the packing n in n m ly. The joints b drawings, wherein:tween the respective parts 3, 6 and 9 are suitably Figure 1 is across-section of; a stufiing-box p p to pr v n l aka f h r h p k- 3oconstructed according to this invention. 'ing or the liquid underpressure. 1

Figure 2 is a cross-section of the plastic cone An annular passage 19,made in the body of tainer. the gland 3 intersects that face of the[gland Figure 3 is an end viewiof the plastic con- Which is adjacent tothe sleeve 6, so connecting tainer. with the helical grooves 22 made inthe sleeve 6. 35 Figure 4 is a cross-section of the sampling The passage29 is extended thru the gland 3 9o device. and terminates in a threadedhole, a sampler Figure 5 is an outer end view of the sampler. body 25being screwed therein. The rotor 26 Figure 6 is a cross-sectional Viewof the and a cap 25 are parts of the sampler which will sampler. beexplained later in more detail. A dowel 10 4a Figure '7 is an innerendView of the sampler. align th gland 3 With the eve 6 So that a Referringnow especially to Figure. 1, a repreproper relation of parts ismaintained. Refersentation of a reciprocating plunger or rod in a' ringW o Figure the section of t e stuffing-boxbuilt according to thisinvention; helical grooves 22 with the end of sleeve 6 are the frameextension 1 contains the stufilng-box indicated and the effect of thesharp lip 28 is also 45 chamber into which the plunger 2 travels toshown. The passage 20 is located between the compress a liquid forexample, the plunger, 2 surfaces of grooves 22 and the outer surface ofbeing guided and aligned by the bushing 8. A the sleeve 6. The dowelhole 10a is the location sleeve 6 is the plastic container used in thisfor the dowel 0 Sh w in Figure device and has a loose fit in thestuffing-box A continuation of passage 19 leadsthru the 5g chamber 1,being held in place by the gland 3. "flange of the gland 3 and in anupward direction,

Gland 3 is tightened by the studs land the ending in athreaded hole. Apipe 11 is threaded nuts 5. into the termination of passage. 19, andthen Before completing the description of the asinto a valve body 12,passage 19 thereby being sembly as shown in Figure 1, itappearsnecescontinued from the gland 3 into the valve body 55 sary to refer toFigure 2, alengthwise cross- 12. The upper part of the valve body 12 isformed into a reservoir, the outside of the latter being threaded toreceive a cap 14. A needle valve 13 is also threaded into the valve body12 and intersects the passage 19 so that the latter may be closed oropened. The cap 14 is threaded to receive an adjusting nut 16 thru whichthe piston rod 17 passes to be attached to the piston 15, the latterresiding in the bore of the reservoir which has been formed in the body12. Y A spring 18 provides means to vary the tension of the pistonagainst any material placed under it. The respective parts 12, 13, 14,15, '16, 1'7 and 18 constitute a spring-loaded device to regulate thepredetermined pressure.

Referring now to Figure 4, a longitudinal cross-section of the sampleras before mentioned in the description of Figure 1, the body 25 isscrewed into the terminating hole of thepassage 20. Passage 2c istherefore continued by passage 20a. The body contains a cylindricalrotor 26 held in place by a cap 21, threaded and screwed over acorresponding thread on the outside of the body 25. The ejectionholesand 31 are aligned so that passages 29, 3c and 31 are openthruout whensorequired. A centrally located pin 2'? is a guide and indicator as willlater be shown.

In Figure 6 is shown a cross-section of Figure kexposing the multiplesampling ports 29. As the rotor 26 is revolved, any of the ports 29 aresuccessively brought into alignment with the passage 20d. and rotor 26may also be turned .so that any of the passages 29 will align withejection ports 30 and 31.

In Figure 5 is shown the cap 21 holding the rotor 26 in such apositionthat passage'29 continues the opening 2%. The guide pin 27,firmly attached to the body 25,.formsa pointer to indicate whenpassages29 and 20a are in line, as the cap 21 is solid. Ejection point31 is shown in line with one of the passages 29.

Figure 7 shows an inner View, the bottom of the sampler, the passages 29and 200. being in line, as are passages 29 and 30.

Referring now to my application for Letters Patent, Serial Number533,430, da ed April 28, '1931, the seventh law of friction, whichstates:

7. Friction is inversely proportional to the rate of seepage how at thesurface of contact between a solid moving and a porous elasticstructure, up to the point of saturation.

Interpreted for plastic packing, the foregoing leans that unless seepageunder pressure can flow thru the packing, the friction will rise-due tothe tendency to occupy a larger volume, until the saturation point stopsany further increase.

The usual method of using plastic packing is to force the materialinto'grooves or reservoirs, the fact that a den e body having fine poresand interstices will become highly saturated, being overlooked. Plasticmaterials trap pressure-and unless the material is in thinsections andintercommunication is established from one part to another, the pressurecannot drop uniformly,

which results in blowing the material out at the points of the greatestpressure change. In Figure 1, the lands 23 and 24 are heroin employed tobreak the continuity of the plastic'body in-a direction parallel to thepressure flow, which causes seepage to flow across each-of the *thinsections.

The arrangement being made so that seepage does flow, the usage ofpressure reaction as-later explained, is made possible, as where thereis a drop of pressure ,in a packing :section, Jfriction is created by anet thrust in the direction of the unbalanced pressure. Saturation, asit aifects plastic bodies, will overcome the foregoing mentioned effect.

In disclosing the operation of this device, the location and dispositionof the plastic material 32 is indicated in Figures 1, 3, i and 6, suchviews apparently being ample for explanation. To start, the grooves 22may be filled with a suitable plastic material before the sleeve 6 isinserted in the stufiing-box chamber 1. Or the needle valve 13 may beopened and the plastic be-placed in the reservoir of the valve body 12Hand forced thru the continuous passages 19, and

'so into grooves 22. Placed under pressure the .plastic material willflow into all of the grooves 19 and be retained on the inner end of thesleeve 6 by'the disc 9. The plastic will then flow into the passages 20and 20a, so into passages 29, if the latter happen to be in line.

* Afterthe passages and grooves are filled with the plastic material thenut 16 may be adjusted so that sufficient :pressure is maintained inthehomogeneous body to correct the density changes .eifected undervibration of the, machine and plunger. On reciprocating plimgers, thepressure against the packing usually rises to a maximumbeginning'withthatpart of the strokecoincident with theopeningof thedischarge valves of the machine. The-packing is therefore subjected toshock and must be arranged for a measure of flexibility. If the packingis toohard or too rigid it will not'form a close contact with theplunger surface and leakage will result. If, however, either themackingstructure is flexible, or its mechanical,arrangementpermits a movementunder the shoclgcontact .with the plunger and packing is close,frictionislessand thepacking-will last longer.

In this invention employing a homogeneous mixture of packing materials,.the density of the packing is maintained by the continuous .rightand'left hand grooves. ,Asthe pressure rises, the plastic material ineach groove is forced back: ward and at an angle with its originalposition; it-alsojta'kes thexthrus't of pressure in acenter line.conforming'with the direction of the. groove. Undermining and washingby the liquid passincfrom one part .of the plastic material to anotheris preventedby the-lands 23 and 24 between each V groove. Eachsectionofplastic material forms a portion of a helical screw, each taking itsshare of the pressure and friction load.

When the shock of sudden pressure rise comes against this design ofpacking, the packing will I be compressed in each groove and will movesidewaysfromgits original position, due to the pitch of the helicalgrooves 22. Thus the plastic is arranged mechanically so that as astructure it can move .under shock, be rearranged momentarily, whichisthe equivalent of fabric flexibility. The plasticunderithis designwill return to its normal vpositionas quickly asthe-pressure isreleased.

.Suddenhigh pressures cause leakage past plastic packing before thetotal area and volume of the pac'kingis acted uponby thepressuretobecome saturated,.and then when saturated, the volume increases and thepacking cannot contract. That is, leakage occurs adjacent to the sourceof pressure action, before the pressure can saturate and change theshape or volume of the packing and force it against the rod. To stopthis leakage along the rod, the sealing mustbe done at the source-ofpressure and practically coincident with=the rise of pressura'to-protectthe packing from cutting and washing. In the helical grooves builtaccording to this invention, the surface of each groove facing thesource of pressure is formed into a lip having an acute angle with therod surface, so that each section of material will be self-set againstthe rod by any unbalanced pressure at the point of contact. A componentof such unbalanced pressure also acts at an angle with the surface ofthe rod coincident with the rise of pressure. Sealing of the packing atthe source of pressure is never later than the rise of pressure andleakage is prevented. If a vacuum on intake strokes occurs before apressure rise, the opposing lip will seal the joint. As both the facesof the grooves 22 and the lands 23 and-24 are lipped, all of the plasticpacking ring sections are subjected to the self-setting action, and thereservoir should be disconnected by closing the needle valve 13 forintermittent or quickly changing pressures. The increase and decrease ofsaturation is assisted by the interposed lands which break the plasticbody into sections, none of which may be considered continuous.

Plastic packing when confined in grooves becomes hard after a period ofuse, the finer particles are washed or rubbed away, the coarserparticles remaining to form a ma The latter will score the rod andfinally loose their original plasticity unless provisions are made tooffset the inevitable changes mentioned. In the presence of hightemperatures plastic packing becomes hardened due to deposits of carbonand other foreign materials in the machine and becomes inoperative in ashort period of time, unless removed.

Another cause of plastic packing becoming inoperative when confined ingrooves is the chemical reaction with the liquids handled. Deposits ofchemicals out of solution are driven into the packing to form hardcompositions unsuitable for packing purposes, due to the loss offlexibility.

In this invention, a sampling device is employed to enable the operatorto determine how much packing should be removed and how often. When thesampling passages 29 are aligned with 20a, that much packing may beremoved from the grooves 22, and from that point adjacent the source ofpressure and temperature, where usage is hardest and hardening willoccur first. New packing is injected by the loading device attached tothe gland 3, which forces the used packing thru passages 29, theoperations being simultaneous and done without hindering operation.After a revoiution of rotor 26 has been made, each movement beingaccomplished by loosening the nut 21, then turning the rotor 26 to matchanother passage 29 with the opening 20a, a rod may be pushed thru thehole 31, so ejecting the sample of packing thru the hole as forexamination.

In those processes of today involving charges of expensive materialwhich must be processed for a stated interval without stoppingoperations, the machines handling the materials must not be stopped forchange of packing.

It is to be believed that the arrangement of this invention will useplastic packing at its highest emciency, convenience of injection andejection, and be an assurance of continuous operation, so necessary inthat class of work involving high pressure and temperatures, shock, andadverse chemical reaction.

The construction as shown is capable of many variations to meet localconditions, and such changes as are embodied in the following claims Ido intend to be within the spirit of this invention.

I claim:

1. A stuffing-box formed around a rod with clearance for said rod,grooves formed in the surface of said stufiing-box wall, means to injectplastic packing materials into said grooves, means to maintain apredetermined pressure within said packing structure, an outlet passagefrom said grooves connected to a sampler device, said sampler devicehave a revolvable drum with multiple compartments therein which may besuccessively positioned to receive plastic packing from said grooves,the plastic packing confined in the compartments of said sampler to beejected successively.

2. A stuffing-box formed around a rod with a clearance for said rod andsubjected to a fluid medium under pressure, a right and a left handedhelical groove formed in the surface of said stuffing-box wall, thesides of said grooves being undercut to form lips facing the source ofsaid medium at an acute angle with the surface of. said rod andinclining away from the source of said medium plastic packing in saidgrooves and means to exert uniform pressure upon said pack- 3. Astuffing-box formed around a rod with a clearance for said rod andsubjected to a fluid medium under pressure, a right and a left handhelical groove formed in the surface of said stuffing-box wall, thesides of said grooves adjacent to the source of said medium being formedat an acute angle with the surface of said rod and inclining toward thesource of said medium plastic packing in said grooves and means to exertuniform pressure upon said packing.

4. A stuffing-box formed around a rod with a clearance for said rod, aright and a left handed groove formed in the surface of saidstufIing-box wall, the sides of said grooves being at an acute anglewith the surface of said rod and converging toward said rod and means toforce a plastic material through said grooves.

5. A stuffing-box formed around a rod with a feed plastic packing underpressure through said grooves and means to remove a sample of saidpacking as desired.

6. A stufiing-box formed around a rod with a clearance for said rod,helical grooves formed in the surface of said stuffing box wall, thesides of said grooves converging toward said rod surface, a reservoircontaining plastic packing materials compressed to a predetermineddegree, and means to force said plastics thru a passage to the helicalgrooves at said predetermined pressure.

7. A stuffing box formed around a rod with a clearance for said rod,helical grooves formed in the inner surface of the wall of said stuffingbox, the sides of said grooves being formed at an acute angle with thesurface of said rod, a reservoir 1 containing plastic materialcompressed to a certain predetermined degree, said reservoir beingconnected to said grooves, and an outlet from said grooves connectedwith the end of said box remote from said reservoir from which packingmay be removed.

HARLEY T. WHEELER.

ill)

